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Bonus Focus - In Defense of Forgetting

By Steven Just, Ed.D.

Forgetting, as everyone knows, is not a good thing. You don’t want to forget your spouse’s birthday or to pay your credit card bill or where you left your car in the shopping mall parking lot. And of course you don’t want to forget job critical information.

Most of us are familiar with the dreaded Ebbinghaus Curve of Forgetting (See Figure 1), which demonstrates that most of what you learn is forgotten very rapidly. (Note: Since Ebbinghaus was using three letter nonsense syllables, it is not surprising that in a few weeks his students forgot most of what they had memorized. For job relevant information, the curve is not quite as scary, but the general point is still correct: Without reinforcement, we will forget large parts of what we learn.)

So then, how is it even possible to suggest that forgetting is a good thing?

First, let’s be clear: We all forget. Whether we want to or not, it’s a natural part of how our brains work. And not only is it a natural part but it is actually beneficial to the learning process in at least three different ways. Let’s see how.

Memory, Forgetting and Learning
To understand how and why we forget], it is important to understand how our memories work. Our memories consist of three parts. (See Figure 2.)

Our sensory storage processes all of the input we receive every waking moment. Some select information from our sensory storage is passed on to our working memory for processing and some subset of that information finds its way to long-term memory. What is of interest is that we forget at each stage of this process – and for good reason.

In Sensory Storage
Forgetting frees our brains to remember what is really important. Do you really need to remember what you ate for lunch three weeks ago Tuesday? Unless you got food poisoning, probably not. Similarly, in a course, not everything you see or hear is important to remember. Some information, if needed, can be looked up and some information is just not that important. Our brains are constantly bombarded by sights, sounds, smells. Imagine if you could remember every sensory input you encounter every day?

There have been a few documented cases of people with 100 percent recall of everything that has ever happened to them. It’s not a positive attribute; in fact it’s debilitating. It causes mental exhaustion. So you do properly forget most of what enters sensory storage -- but some very small subset is passed on to working memory.

In Working Memory
Working memory consists of a central executive for processing information and a limited amount of storage for holding the information being processed. (See Figure 3.)
It was previously believed that working memory could hold 7 +/-2 pieces of information (this was known as Miller’s Magic Number) but more recent research shows that the number is actually only three or four.

Overwhelming our limited working memory is rather easy and is known as cognitive overload.` Proper instruction is designed to manage cognitive load. In fact, there are entire books written on this subject. (I recommend The Cambridge Handbook of Multimedia Learning by Richard Mayer.)

During a learning experience you don’t need to remember everything. In fact you can’t possibly remember everything -- working memory is too limited. Much of the detail is properly forgotten to free up working memory space for what is important. And what is important is transferred to long-term memory where it is remembered forever – or maybe not.

In Long-Term Memory
What gets stored in our long term memories is subject to storage decay (i.e. forgetting). But, it is also true that a little forgetting helps in remembering. Deep learning occurs when memories are stored in long term memory and stabilized. This is called memory consolidation.

An effective method for consolidating a memory is to use active learning techniques: Retrieve the memory from long-term memory, bring it into working memory, process it, and then re-store (re-encode) it in long-term memory. (See Figure 4.)
The well-known spacing effect (spacing learning over a period of time) uses this process. But one outstanding question about spaced learning is: What is the optimal spacing period? Many studies have shown that optimal retrieval and reconsolidation occurs when the learner is just at the point of forgetting.

In 1989 Banaji and Crowder wrote: “As an empirical rule, the generalization seems to be that a repetition will help most if the material had been in storage long enough to be just on the verge of being forgotten.”

So, remember (pun intended) not all forgetting is bad for you or your learners.